1. To determine the syntactic structure of a sentence or other
utterance (close to the standard English meaning). “That was the one
I saw you.” “I can't parse that.”

2. More generally, to understand or comprehend. “It's very
simple; you just kretch the glims and then aos the zotz.” “I
can't parse that.”

3. Of fish, to have to remove the bones yourself. “I object
to parsing fish”, means “I don't want to get a whole fish, but
a sliced one is okay”. A parsed
fish has been deboned. There is some controversy over whether
unparsed should mean
‘bony’, or also mean ‘deboned’.